I did mine in 2x2 sections due to the Makerbot constraints. The 10cm build platform means that you could barely do a (roughly) 4" object but that doesn't allow for any outside details or variance. 3" (7-8cm) objects would be quite doable and I considered trying to think up a system based around 3x3 tiles, but it doesn't work out very cleanly for things like corridors and intersections. So 2x2 it was.
If you come up with a way to easily interlock square sections I might just swipe it. The ones I considered either relied on needing snug connectors that would push the limits of the consistent repeatability of a Makerbot or else involved connecting joints that were printed right on, but that limit
s what orientations pieces can be attached to each other.
of course my design had the advantage of having each section stand-alone so there is less need to brace against other pieces or slippage.
If you think of something better I suspect it will get copied far and wide.